Monday, December 3, 2018

Catching Up Almost Month Since Last Post

Outdoor flying in Minnesota has pretty much ended for me and I am trying to repair planes before building new ones for 2019. I have done some quicker builds between repairs; two rocket gliders, Science Olympiad catapult glider, and a Sig Cub setup for electric with STRIX timer. I did get one launch of Aleda R boost glider in the cold that went pretty well, just some stall in the glide. 

New Gollywock Fuselage Covered with Clear Mylar
Esaki Tissue Added

My mother passed away a couple of weeks ago and I have been busy with things related to her death. I did get the chance to give a science demo on electric motors, model solar cars, and model wind turbines. Made a visit to an after school class doing Science Olympiad and demonstrated my Protégé catapult glider. I hope to spend more time working with students and science related activities but I do not find much interest in that locally. 

Aleda R Boost Glider

Eureka E36 Short Test Flight

Reflecting on my free flight flying this year, I want to improve on my building and covering for next seasons models. I have been trying the tissue over mylar in more models and it is working better for me as I get the tissue attached without loose spots or wrinkles. On my Euerka e36 I recovered the wing with Polyspan lite which keeps the structure rigid in humid conditions but it is hard to fill the covering without using too much dope. I try to spot the places where tiny holes appear instead of so many coats on the whole structure. To get the stick joints closer to perfect in construction I ordered a Fourmost Miter Sander.

Sig Cub Electric

For several years I did not fly any model airplanes powered by a glow engine, only flew gliders or electric. At first I did not miss the mess or the noise but as I got into outdoor competition free flight I wanted to try glow engines again. Part of this was to be able to fly in more events, part has to do with nostalgia, and it is fun working with the engines. A friend even sent me a couple of model diesel engines which will be fun to get running. 

ED Hunter Diesel

Test Running Cox Medallion .049

In the back of mind I am thinking of attending a distant free flight contest this winter. Maybe not to fly or maybe fly an event that lends to easy airline travel.


Bill Kuhl

Related Links





Thursday, November 8, 2018

Importance of Materials in Model Aviation

After the end of the outdoor free flight contest season I have been reflecting on what I need to improve on for the future. I have also spent more time reading and watching videos on history and science. One aspect of my model building that I try to improve on is “materials”. In studying history, the most important discoveries that enabled new innovations, were the discovery of new materials. With the discovery of iron and later improving on this to create steel, so many things could be built or improved on as an example.

Witch Hawk 500 - Polyspan & Silkspan Covering


The model airplanes I most enjoy building are built primarily of balsa wood. Balsa is very strong for its weight and great to work with simple hand tools. It does vary in weight and hardness considerably and matching the proper density for the requirements needed in the model construction is critical to build a competitive free flight model. Not paying enough attention to this I have built models that were too heavy or were not strong enough in critical places and broke just from flight loads. Not only is the density of balsa important but also the grain types created by how the balsa was cut from the balsa logs.

1/2 A Streak Wing Does Not Sag with Polyspan Lite


Another part of the model construction I have been trying to refine is the proper covering material for the type of model I am building. In the past I most often used a plastic iron-on covering when possible, for smaller models it was tissue paper. For the past couple of years I have had a fascination with the older free flight models. With the older designs the structure was lacking the rigidity needed without using a covering material that gave the structure the strength needed. Yet another aspect of the covering selection that became apparent with the past flying season was what humidity did to the covering. Esaki tissue which is really the only choice for many smaller models starts to sag terribly in early morning or late evening when I often fly. Besides taking on extra weight now that the covering is no longer tight on the model, the structure becomes less rigid.

Wilbur Center Section Repaired with Tissue over Mylar


Last winter in my building I tried covering with Polyspan and using mylar under the Esaki tissue. Polyspan does not change with water; to shrink it heat is used. It only comes in white and needs to be filled with nitrate dope before applying the color. I had purchased airbrush equipment and this worked well for finishing the Polyspan. There is also a Polyspan Lite which is considerably lighter but harder to fill. I used this on smaller gas models; it did stay tight but will puncture easily. 


New Gollywock Tissue over Mylar


Many people recommend covering models with ¼ mylar and then covering over this with tissue. It sounded like a lot of work but I did try it on a New Gollywock model I was building. On the first model I believe I did not get the tissue attached properly resulting in loose spots and wrinkles. In doing a repair on center section of Wilbur rubber model I did a better job of sealing the tissue to the mylar. The covering does not sag in humid conditions but the tissue will still take on weight from the water.

Eureka e36 Wing Recover with Polyspan Lite - Sagging Tissue on Stab



For me the challenges of getting the choices closer to optimum in building an outdoor free flight model is what makes it so fun. No doubt with more experience I will become more uniform on the choices of wood and covering material. What I appreciate with the rules for the classes of free flight models I fly is that I am forced to do this and cannot just buy a high-tech composite model that was constructed in molds.

Bill Kuhl
http://www.ideas-inspire.com


Friday, November 2, 2018

Free Flight Fun Projects & Repairs

After the outdoor free flight contest season has finished I have been busy repairing planes and trying some quick new planes. In a previous post I had mentioned working with the STRIX electric timer and flying on a direct drive 7 mm motor. Last weekend I had some good flights using this setup in an AMA Maxi Jr rubber model converted to electric. As I got the turn circle dialed in the flights became higher lasting about 35 seconds on the 10 second power run. The last flight ended when a dog grabbed the plane by the wing and started to carry it back. Only the tissue was ripped. I have to believe with a lighter plane a minute flight is possible, which would be about perfect for a small flying site.


NJAPF Fuselage Repaired 


Only Damage After Carried by Dog

AMA Maxi Jr Electric


At the last outdoor Minnesota contest I flew my NJAPF p30 and the DT line broke, after the contest I decided it was time to recover the fuselage that had numerous patches. What surprised me a little was there were broken glue joints that the covering had hidden. After repairing the structure and twisting it to check for more questionable joints, I did find more. My plan is to replace the viscous stab DT system with a wing pop off using a fuse.


Eureka E36 Test Flight after Repairs


After a crash at the Nats I finished repairs on my Eureka e36 NOS. The wing was recovered with Polyspan Lite because I did not like the sagging tissue in humid conditions. My repair in one spar in the wing was not adequate as it broke again on the first low level DT landing. This has been repaired and more short flights went well. 


FAC Tic Catapult Gliders


G12 Catapult Glider


A couple of simple catapult gliders were finished the first being the FAC Tic from Easybuilt which comes in a 2-pack. The first one I messed up in that I did not get the dihedral blocked up well when using Testors glue, trying to fix this I did not do the best job either. The second one I used CA and got everything aligned. This glider flies really well for only having a 6” wingspan. I also finished up a second G12 Catapult glider with the flapped trailing edge. Richard Bertrand uses this glider in his Free Flight Rescue program for kids. The glider is stable and can handle a full stretch launch with ¼” rubber.


Aleda R Boost Glider
Switchblade S Wing Forward


Wing Back


  For something different I have built two rocket glider kits purchased from J&H Aerospace. One is a boost glider where the motor tube and nose cone separate from a glider. The other is a swing wing glider that has the wing halves move forward when the ejection charge releases the tension on two lines holding the wing halves swept back 90 degrees. This should be fun to see go up.

I have a new fuselage to build for a New Gollywock and then plan to start building some new models.

Bill Kuhl
http://www.ideas-inspire.com

Related Links

https://jhaerospace.com/product/aleda-r-boost-glider/  Aleda R Boost Glider
https://jhaerospace.com/product/switchblade-s-rocket-glider-kit/  Switchblade S Rocket Glider
https://easybuiltmodels.com/g09.htm Easy Built FAC Tic catapult glider

Monday, October 22, 2018

Dewey Bird Control Line Adventures 2018

My first real start in model aviation was with ½ A control line planes, I remember building a Carl Goldberg Stuntman 23 when I was 9 years old. Last year in the fall I was trying to fly an electric control line for the first time after no control line flying for many years. I was running out of warm weather and tried to fly in too much wind with too long of lines. The plane was repaired and flown successfully but it looked like this plane was rather fragile to be crashing from beginner mistakes, so over the winter I built a Sig ½ A Dewey Bird to be powered with a Cox Babe Bee .049. 


1/2 A Dewey Bird



Bottom of Piston shows Where Connecting Rod Came Apart


The Cox Babe Bee is another story, I saw it on a hobby shop counter. The owner said it didn't run and that I could have it. It felt like something was broken, it turned out the connecting rod had ripped out of where it connects to the piston. I thought maybe it had over heated as it had a 7-6 wood propeller on it but people tell me larger propellers are run on .049's for Texaco event. I found a piston in my junk parts collection and the engine ran great.



Dewey Bird in Stooge


Electric Control Line

Free flight kept me really busy for most of the summer but after the Nats I fly my Dewey Bird for first time. There was no one to help so I made a stooge using a couple pieces of wood in a drillpress vise. I was using 35' .012 metal lines which I had from childhood. I think 26' lines are recommended, it flew on the long lines but tension was not great. Next time out I flew the Dewey Bird on 26 foot Spider wire lines which were better but it was really gusty that day. It was a good lesson in keeping the line tight when a gust hit it. For the next time flying, I added sidethrust and moved leadouts back. It might have helped a little. Again I tried to loop and stepped backwards really quick to try to regain tension. I tripped in the tall grass and fell on my butt. One more try and the plane went around once but lost tension and went up for another loop but crashed on the bottom. Only broke the propeller but I fell again.


Damage from Slack Lines

 Next time out I tried loops twice and crashed but no damage. Then I leaned the motor out more, I was afraid it would get too lean in the air but it didn't. Now tension was better, I tried a loop and it went around easy with plenty of room to spare. Tried it again and it went around fine. Fly more laps and then decided to try one more time but hesitated and the plane went into the wind and there was slack in the lines. The crash did damage this time, it only took a few minutes to fix when I got home.  


Add Weight to Tail  to Move CG Back

Now it gets dark so early and it has been windy for a couple of weeks. One evening I flew my electric control line again and it flew well.  Then tension is much better with this plane but I still want to get more practice with the ½ A.  I still have a Carl Goldberg Buster with a Fox .35 on it from my childhood I want to fly that again also. 


Goldberg Buster


I realize it would no doubt be easier to learn aerobatic maneuvers with a larger plane; at this point I am just too afraid of crashing a larger plane. There is also the challenge of pushing for higher performance with a small plane. 

Bill Kuhl





Wednesday, October 17, 2018

Experiments with STRIX Free Flight Electric Motor Timer

In the past few weeks I have been experimenting with using a small electric motor timer that I purchased from the RMRC company for under $7. An online friend had sent me a link to this and I ordered a couple of the timers. After receiving the timer I discovered it used the larger JST 2.0 plug in connecting to the battery, so another order was placed for a couple of batteries and a charger that fits this connector. The connector is slightly larger than the connector used on the Eflite planes I have.  In the future I want to replace the connector on the timer with the more standard connector on a sample timer. This would make it possible to use batteries and chargers that many people already have.


Electric Powered Guillow's Cloud Buster


STRIX Timer, motor, and battery
My first test aircraft was an injected foam glider the Guillow’s Skyraider, the motor was mounted on a pylon I constructed out of balsa, everything held together with low temperature hot glue.  The total weight was 56 grams which is too heavy for much of a climb. For a propeller I used one from an Aero Ace biplane I had, it did not overheat the motor like when trying an E20 size propeller. The specifications of the timer call for 6 mm or 7 mm motor, I used 7 mm motors from RMRC which come for in packages of four motors, two wired for clockwise and two counter-clockwise. 


Robbed the Propellers



Comparison of Plug Sizes


Charging Board and AC Power Supply, can use Lipo Battery 3S or 4S

The foam glider might be great if it were lighter, the first flights it only got maybe 20 feet high. I removed some foam from the glider and it started climbing higher. The stability was just okay, it tended to wander around in the sky but it always survived a hard landing.


Electric Foam Glider





For the next plane I wanted to try a balsa plane with a really simple structure, I found a Super Dart in my basement which is similar to Sig Thermal Dart, flat pointy wings. A real short test fight with timer a battery taped on showed that this will climb better with a total weight of 23 grams. The weather has turned windy all the time which is bad for test flying. After another flight in the wind the second flight resulted in the fuselage breaking in multiple places. In the future would like to try this with a basswood fuselage as I would like to find really simple planes for the electric setup.


Super Dart Crash Damage

As I see this timer/motor setup, it would be good for kids flying in a schoolyard, the maximum run is only 10 seconds. You can select between 5,8, or 10 seconds very easily. With the battery that I found to fit the connector  at 220 mah it will give many flights on a single charge. The battery is rather heavy at 6 grams, timer 3 grams, and motor at 3 grams. The increased weight over a rubber motor would explain why crashes on models designed for rubber power would be more damaging. 


Cloud Buster Electric


The last model I have tried was a Guillow’s Cloud Buster built a long time ago. I think this model will work well but again I tried to fly it in way too much wind. First short flight it went too much right but recovered. I added too much weight on left wingtip to correct on second flight and it hit the ground in a left spiral dive breaking the pylon. I started building a new pylon that I can mount the timer and battery inside and have the wing held on by rubber bands. This type of model I have to believe should climb high enough to glide around for an additional 30 seconds or more. Kids do not even have to wind the rubber which should not be a big deal but I find some have trouble. I am looking for other sources of motors and propellers at an inexpensive price. I will write another article as I progress with this farther.


Crash in Progress



Rebuilding Pylon
Update 10/18/2018

It was relatively calm this morning as the sun was coming up but there was frost in the grass. I was determined to get in more test flights on the Cloud Buster I rebuilt the pylon for with the wing now held by a rubber band before work.  First flight at 5 seconds looked alright so went to 8 seconds. The plane had too much right turn, adding clay to wingtip had it going straight with a series of small stalls, taking a small amount off it was better but it seemed to easily circle either direction.  The plane climbs but not very steep, I think more wing area might help. Someone suggested the AMA Maxi Jr might work which I have and will probably try, it has a constant chord wing. The Cloud Buster tapers to thin at the tips.  If I used a lighter battery I think that would help too.


Cloud Buster with New Pylon

12/11/2018 - Sig Cub Electric




Bill Kuhl
http://www.ideas-inspire.com


Related Links

https://www.readymaderc.com/products/details/strix-free-flight-motor-timer  Link to Timer

https://www.guillow.com/skyraider.aspx?fbclid=IwAR0SfrzjxBnE65FCku_MfoVtW3UlShyPUQRYGQ5_-Kr36en5CPV7TcFUusI  
Foam Guillow's Glider

https://www.guillow.com/cloudbuster.aspx   Guillow’s Cloud Buster

Monday, October 8, 2018

Last 2018 Free Flight Contest Minnesota

I was so close to not attending the last 2018 outdoor free flight contest in Minnesota because of the wind prediction and threat of rain. It was cool, dark, and windy at times but the direction gave a good deal of room to drift without getting into trees or corn. For me it was one small problem after another but I still had a great time. At least I should have more time now to get my equipment better prepared for next year.




First Wilbur Flight was high enough for prop to fold





To start flying I decided to take out my Wilbur rubber model that normally flies great but has had issues at the last two contests. Two months ago the center of the wing folded on launch and last contest it would barely climb. The blades were loose on the hub which I repaired and it climbed better in test flight but I did not get up to full winds. At this contest the counter on my winder came loose and the screw was stripped out so I had to count winds and with weird gear ratio that isn’t easy. First test flight it did better than when the blades were loose but after that it just got worse.


Bearing that is Dragging


When I picked up the model with turns left the propeller would barely turn over. The metal sleeve that goes into noseblock hole was loose because it was trying to turn in the balsa. Someone squirted some fuel into the ball bearing thrust bearing that appeared to be dragging. After I glued the sleeve I tried a couple more flights and result was the same. When I got home I looked closer at the ball bearing and it seemed like the two sides of the bearing could be wiggled apart farther than the same type of bearing in another airplane. At times it appeared to turn real hard but not all the time. Replacing the bearing would not be easy as the propeller shaft would have to be broken loose in front where it attaches to the hub.


P30 Still on the Field


For the P30 event I brought my older NJAPF p30 along because I didn’t want to risk my Polecat X in the wind. The fuselage really needs a recovering but the DT line broke just as I tried to wrap it around the rear peg. I didn’t have any line along so I bypassed the DT and hoped for the best. I did not wind it too much because I did not have a counter but I did have a torque meter for P30. Problem was I was not sure what torque would break the rubber. At least I got in 3 official flights and did not lose the model.


No DT Sunday P30


There was another guy flying P30 that did not use a DT because he thought the popoff wing line was causing a trim problem. He made a joke about it being “no DT Sunday” and needing to build a new model. I timed his flight and the model really climbed high, it must have been in enough lift to maintain although it wasn’t climbing any higher. After 2 ½ minutes I lost sight of it but he was able to find the model without a tracker. 


1/2 A Streak Missed Puddle


I flew my ½ A Streak after that just for fun. It was a little harder getting the glow motor running at 50 degrees than when it is 80 degrees. The needle valve needed some adjusting but then it ran well and pulled the plane to a good height. Transition was good and the glide did not stall and was in a gentle right circle, just came down too fast.




My DLG changed trim from last time flying, thought I was getting it readjusted and then it crashed. Like every contest the time just went too fast, I leave rather early because it is a 3 hour drive home. Closing with more pictures from the contest.


Gary Oakin's Rubber Model



Dave Braun's Scale Model Did not Like the Wind













Bill Kuhl
http://www.ideas-inspire.com